source4/ntp_signd/ntp_signd.c

   1 /*
   2    Unix SMB/CIFS implementation.
   3
   4    NTP packet signing server
   5
   6    Copyright (C) Andrew Bartlett <abartlet@samba.org> 2005
   7    Copyright (C) Andrew Tridgell        2005
   8    Copyright (C) Stefan Metzmacher      2005
   9
  10    This program is free software; you can redistribute it and/or modify
  11    it under the terms of the GNU General Public License as published by
  12    the Free Software Foundation; either version 3 of the License, or
  13    (at your option) any later version.
  14
  15    This program is distributed in the hope that it will be useful,
  16    but WITHOUT ANY WARRANTY; without even the implied warranty of
  17    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  18    GNU General Public License for more details.
  19
  20    You should have received a copy of the GNU General Public License
  21    along with this program.  If not, see <http://www.gnu.org/licenses/>.
  22 */
  23
  24 #include "includes.h"
  25 #include "smbd/service_task.h"
  26 #include "smbd/service.h"
  27 #include "smbd/service_stream.h"
  28 #include "smbd/process_model.h"
  29 #include "lib/stream/packet.h"
  30 #include "lib/tsocket/tsocket.h"
  31 #include "libcli/util/tstream.h"
  32 #include "librpc/gen_ndr/ndr_ntp_signd.h"
  33 #include "param/param.h"
  34 #include "dsdb/samdb/samdb.h"
  35 #include "auth/auth.h"
  36 #include "libcli/security/security.h"
  37 #include "lib/ldb/include/ldb.h"
  38 #include "lib/ldb/include/ldb_errors.h"
  39 #include "../lib/crypto/md5.h"
  40 #include "system/network.h"
  41 #include "system/passwd.h"
  42
  43 /*
  44   top level context structure for the ntp_signd server
  45 */
  46 struct ntp_signd_server {
  47         struct task_server *task;
  48         struct ldb_context *samdb;
  49 };
  50
  51 /*
  52   state of an open connection
  53 */
  54 struct ntp_signd_connection {
  55         /* stream connection we belong to */
  56         struct stream_connection *conn;
  57
  58         /* the ntp_signd_server the connection belongs to */
  59         struct ntp_signd_server *ntp_signd;
  60
  61         struct tstream_context *tstream;
  62
  63         struct tevent_queue *send_queue;
  64 };
  65
  66 static void ntp_signd_terminate_connection(struct ntp_signd_connection *ntp_signd_conn, const char *reason)
  67 {
  68         stream_terminate_connection(ntp_signd_conn->conn, reason);
  69 }
  70
  71 static NTSTATUS signing_failure(struct ntp_signd_connection *ntp_signdconn,
  72                                 TALLOC_CTX *mem_ctx,
  73                                 DATA_BLOB *output,
  74                                 uint32_t packet_id)
  75 {
  76         struct signed_reply signed_reply;
  77         enum ndr_err_code ndr_err;
  78
  79         signed_reply.op = SIGNING_FAILURE;
  80         signed_reply.packet_id = packet_id;
  81         signed_reply.signed_packet = data_blob(NULL, 0);
  82
  83         ndr_err = ndr_push_struct_blob(output, mem_ctx,
  84                                        lp_iconv_convenience(ntp_signdconn->ntp_signd->task->lp_ctx),
  85                                        &signed_reply,
  86                                        (ndr_push_flags_fn_t)ndr_push_signed_reply);
  87
  88         if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
  89                 DEBUG(1,("failed to push ntp error reply\n"));
  90                 return ndr_map_error2ntstatus(ndr_err);
  91         }
  92
  93         return NT_STATUS_OK;
  94 }
  95
  96 /*
  97   receive a full packet on a NTP_SIGND connection
  98 */
  99 static NTSTATUS ntp_signd_process(struct ntp_signd_connection *ntp_signd_conn,
 100                                   TALLOC_CTX *mem_ctx,
 101                                   DATA_BLOB *input,
 102                                   DATA_BLOB *output)
 103 {
 104         const struct dom_sid *domain_sid;
 105         struct dom_sid *sid;
 106         struct sign_request sign_request;
 107         struct signed_reply signed_reply;
 108         enum ndr_err_code ndr_err;
 109         struct ldb_result *res;
 110         const char *attrs[] = { "unicodePwd", "userAccountControl", "cn", NULL };
 111         struct MD5Context ctx;
 112         struct samr_Password *nt_hash;
 113         uint32_t user_account_control;
 114         int ret;
 115
 116         ndr_err = ndr_pull_struct_blob_all(input, mem_ctx,
 117                                            lp_iconv_convenience(ntp_signd_conn->ntp_signd->task->lp_ctx),
 118                                            &sign_request,
 119                                            (ndr_pull_flags_fn_t)ndr_pull_sign_request);
 120
 121         if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
 122                 DEBUG(1,("failed to parse ntp signing request\n"));
 123                 dump_data(1, input->data, input->length);
 124                 return ndr_map_error2ntstatus(ndr_err);
 125         }
 126
 127         /* We need to implement 'check signature' and 'request server
 128          * to sign' operations at some point */
 129         if (sign_request.op != SIGN_TO_CLIENT) {
 130                 return signing_failure(ntp_signd_conn,
 131                                        mem_ctx,
 132                                        output,
 133                                        sign_request.packet_id);
 134         }
 135
 136         /* We need to implement 'check signature' and 'request server
 137          * to sign' operations at some point */
 138         if (sign_request.version != NTP_SIGND_PROTOCOL_VERSION_0) {
 139                 return signing_failure(ntp_signd_conn,
 140                                        mem_ctx,
 141                                        output,
 142                                        sign_request.packet_id);
 143         }
 144
 145         domain_sid = samdb_domain_sid(ntp_signd_conn->ntp_signd->samdb);
 146         if (domain_sid == NULL) {
 147                 return signing_failure(ntp_signd_conn,
 148                                        mem_ctx,
 149                                        output,
 150                                        sign_request.packet_id);
 151         }
 152
 153         /* The top bit is a 'key selector' */
 154         sid = dom_sid_add_rid(mem_ctx, domain_sid,
 155                               sign_request.key_id & 0x7FFFFFFF);
 156         if (sid == NULL) {
 157                 talloc_free(mem_ctx);
 158                 return signing_failure(ntp_signd_conn,
 159                                        mem_ctx,
 160                                        output,
 161                                        sign_request.packet_id);
 162         }
 163
 164         ret = ldb_search(ntp_signd_conn->ntp_signd->samdb, mem_ctx,
 165                                  &res,
 166                                  samdb_base_dn(ntp_signd_conn->ntp_signd->samdb),
 167                                  LDB_SCOPE_SUBTREE,
 168                                  attrs,
 169                                  "(&(objectSid=%s)(objectClass=user))",
 170                                  dom_sid_string(mem_ctx, sid));
 171         if (ret != LDB_SUCCESS) {
 172                 DEBUG(2, ("Failed to search for SID %s in SAM for NTP signing: "
 173                           "%s\n",
 174                           dom_sid_string(mem_ctx, sid),
 175                           ldb_errstring(ntp_signd_conn->ntp_signd->samdb)));
 176                 return signing_failure(ntp_signd_conn,
 177                                        mem_ctx,
 178                                        output,
 179                                        sign_request.packet_id);
 180         }
 181
 182         if (res->count == 0) {
 183                 DEBUG(5, ("Failed to find SID %s in SAM for NTP signing\n",
 184                           dom_sid_string(mem_ctx, sid)));
 185         } else if (res->count != 1) {
 186                 DEBUG(1, ("Found SID %s %u times in SAM for NTP signing\n",
 187                           dom_sid_string(mem_ctx, sid), res->count));
 188                 return signing_failure(ntp_signd_conn,
 189                                        mem_ctx,
 190                                        output,
 191                                        sign_request.packet_id);
 192         }
 193
 194         user_account_control = ldb_msg_find_attr_as_uint(res->msgs[0],
 195                                                          "userAccountControl",
 196                                                          0);
 197
 198         if (user_account_control & UF_ACCOUNTDISABLE) {
 199                 DEBUG(1, ("Account %s for SID [%s] is disabled\n",
 200                           ldb_dn_get_linearized(res->msgs[0]->dn),
 201                           dom_sid_string(mem_ctx, sid)));
 202                 return NT_STATUS_ACCESS_DENIED;
 203         }
 204
 205         if (!(user_account_control & (UF_INTERDOMAIN_TRUST_ACCOUNT|UF_SERVER_TRUST_ACCOUNT|UF_WORKSTATION_TRUST_ACCOUNT))) {
 206                 DEBUG(1, ("Account %s for SID [%s] is not a trust account\n",
 207                           ldb_dn_get_linearized(res->msgs[0]->dn),
 208                           dom_sid_string(mem_ctx, sid)));
 209                 return NT_STATUS_ACCESS_DENIED;
 210         }
 211
 212         nt_hash = samdb_result_hash(mem_ctx, res->msgs[0], "unicodePwd");
 213         if (!nt_hash) {
 214                 DEBUG(1, ("No unicodePwd found on record of SID %s "
 215                           "for NTP signing\n", dom_sid_string(mem_ctx, sid)));
 216                 return signing_failure(ntp_signd_conn,
 217                                        mem_ctx,
 218                                        output,
 219                                        sign_request.packet_id);
 220         }
 221
 222         /* Generate the reply packet */
 223         signed_reply.packet_id = sign_request.packet_id;
 224         signed_reply.op = SIGNING_SUCCESS;
 225         signed_reply.signed_packet = data_blob_talloc(mem_ctx,
 226                                                       NULL,
 227                                                       sign_request.packet_to_sign.length + 20);
 228
 229         if (!signed_reply.signed_packet.data) {
 230                 return signing_failure(ntp_signd_conn,
 231                                        mem_ctx,
 232                                        output,
 233                                        sign_request.packet_id);
 234         }
 235
 236         memcpy(signed_reply.signed_packet.data, sign_request.packet_to_sign.data, sign_request.packet_to_sign.length);
 237         SIVAL(signed_reply.signed_packet.data, sign_request.packet_to_sign.length, sign_request.key_id);
 238
 239         /* Sign the NTP response with the unicodePwd */
 240         MD5Init(&ctx);
 241         MD5Update(&ctx, nt_hash->hash, sizeof(nt_hash->hash));
 242         MD5Update(&ctx, sign_request.packet_to_sign.data, sign_request.packet_to_sign.length);
 243         MD5Final(signed_reply.signed_packet.data + sign_request.packet_to_sign.length + 4, &ctx);
 244
 245
 246         /* Place it into the packet for the wire */
 247         ndr_err = ndr_push_struct_blob(output, mem_ctx,
 248                                        lp_iconv_convenience(ntp_signd_conn->ntp_signd->task->lp_ctx),
 249                                        &signed_reply,
 250                                        (ndr_push_flags_fn_t)ndr_push_signed_reply);
 251
 252         if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
 253                 DEBUG(1,("failed to push ntp error reply\n"));
 254                 return ndr_map_error2ntstatus(ndr_err);
 255         }
 256
 257         return NT_STATUS_OK;
 258 }
 259
 260 /*
 261   called on a tcp recv
 262 */
 263 static void ntp_signd_recv(struct stream_connection *conn, uint16_t flags)
 264 {
 265         struct ntp_signd_connection *ntp_signd_conn = talloc_get_type(conn->private_data,
 266                                                         struct ntp_signd_connection);
 267         ntp_signd_terminate_connection(ntp_signd_conn,
 268                                        "ntp_signd_recv: called");
 269 }
 270
 271 /*
 272   called when we can write to a connection
 273 */
 274 static void ntp_signd_send(struct stream_connection *conn, uint16_t flags)
 275 {
 276         struct ntp_signd_connection *ntp_signd_conn = talloc_get_type(conn->private_data,
 277                                                         struct ntp_signd_connection);
 278         /* this should never be triggered! */
 279         ntp_signd_terminate_connection(ntp_signd_conn,
 280                                        "ntp_signd_send: called");
 281 }
 282
 283 struct ntp_signd_call {
 284         struct ntp_signd_connection *ntp_signd_conn;
 285         DATA_BLOB in;
 286         DATA_BLOB out;
 287         uint8_t out_hdr[4];
 288         struct iovec out_iov[2];
 289 };
 290
 291 static void ntp_signd_call_writev_done(struct tevent_req *subreq);
 292
 293 static void ntp_signd_call_loop(struct tevent_req *subreq)
 294 {
 295         struct ntp_signd_connection *ntp_signd_conn = tevent_req_callback_data(subreq,
 296                                       struct ntp_signd_connection);
 297         struct ntp_signd_call *call;
 298         NTSTATUS status;
 299
 300         call = talloc(ntp_signd_conn, struct ntp_signd_call);
 301         if (call == NULL) {
 302                 ntp_signd_terminate_connection(ntp_signd_conn,
 303                                 "ntp_signd_call_loop: "
 304                                 "no memory for ntp_signd_call");
 305                 return;
 306         }
 307         call->ntp_signd_conn = ntp_signd_conn;
 308
 309         status = tstream_read_pdu_blob_recv(subreq,
 310                                             call,
 311                                             &call->in);
 312         TALLOC_FREE(subreq);
 313         if (!NT_STATUS_IS_OK(status)) {
 314                 const char *reason;
 315
 316                 reason = talloc_asprintf(call, "ntp_signd_call_loop: "
 317                                          "tstream_read_pdu_blob_recv() - %s",
 318                                          nt_errstr(status));
 319                 if (reason == NULL) {
 320                         reason = nt_errstr(status);
 321                 }
 322
 323                 ntp_signd_terminate_connection(ntp_signd_conn, reason);
 324                 return;
 325         }
 326
 327         DEBUG(10,("Received NTP TCP packet of length %lu from %s\n",
 328                  (long) call->in.length,
 329                  tsocket_address_string(ntp_signd_conn->conn->remote_address, call)));
 330
 331         /* skip length header */
 332         call->in.data +=4;
 333         call->in.length -= 4;
 334
 335         status = ntp_signd_process(ntp_signd_conn,
 336                                      call,
 337                                      &call->in,
 338                                      &call->out);
 339         if (! NT_STATUS_IS_OK(status)) {
 340                 const char *reason;
 341
 342                 reason = talloc_asprintf(call, "ntp_signd_process failed: %s",
 343                                          nt_errstr(status));
 344                 if (reason == NULL) {
 345                         reason = nt_errstr(status);
 346                 }
 347
 348                 ntp_signd_terminate_connection(ntp_signd_conn, reason);
 349                 return;
 350         }
 351
 352         /* First add the length of the out buffer */
 353         RSIVAL(call->out_hdr, 0, call->out.length);
 354         call->out_iov[0].iov_base = call->out_hdr;
 355         call->out_iov[0].iov_len = 4;
 356
 357         call->out_iov[1].iov_base = call->out.data;
 358         call->out_iov[1].iov_len = call->out.length;
 359
 360         subreq = tstream_writev_queue_send(call,
 361                                            ntp_signd_conn->conn->event.ctx,
 362                                            ntp_signd_conn->tstream,
 363                                            ntp_signd_conn->send_queue,
 364                                            call->out_iov, 2);
 365         if (subreq == NULL) {
 366                 ntp_signd_terminate_connection(ntp_signd_conn, "ntp_signd_call_loop: "
 367                                 "no memory for tstream_writev_queue_send");
 368                 return;
 369         }
 370
 371         tevent_req_set_callback(subreq, ntp_signd_call_writev_done, call);
 372
 373         /*
 374          * The NTP tcp pdu's has the length as 4 byte (initial_read_size),
 375          * packet_full_request_u32 provides the pdu length then.
 376          */
 377         subreq = tstream_read_pdu_blob_send(ntp_signd_conn,
 378                                             ntp_signd_conn->conn->event.ctx,
 379                                             ntp_signd_conn->tstream,
 380                                             4, /* initial_read_size */
 381                                             packet_full_request_u32,
 382                                             ntp_signd_conn);
 383         if (subreq == NULL) {
 384                 ntp_signd_terminate_connection(ntp_signd_conn, "ntp_signd_call_loop: "
 385                                 "no memory for tstream_read_pdu_blob_send");
 386                 return;
 387         }
 388         tevent_req_set_callback(subreq, ntp_signd_call_loop, ntp_signd_conn);
 389 }
 390
 391 static void ntp_signd_call_writev_done(struct tevent_req *subreq)
 392 {
 393         struct ntp_signd_call *call = tevent_req_callback_data(subreq,
 394                         struct ntp_signd_call);
 395         int sys_errno;
 396         int rc;
 397
 398         rc = tstream_writev_queue_recv(subreq, &sys_errno);
 399         TALLOC_FREE(subreq);
 400         if (rc == -1) {
 401                 const char *reason;
 402
 403                 reason = talloc_asprintf(call, "ntp_signd_call_writev_done: "
 404                                          "tstream_writev_queue_recv() - %d:%s",
 405                                          sys_errno, strerror(sys_errno));
 406                 if (!reason) {
 407                         reason = "ntp_signd_call_writev_done: "
 408                                  "tstream_writev_queue_recv() failed";
 409                 }
 410
 411                 ntp_signd_terminate_connection(call->ntp_signd_conn, reason);
 412                 return;
 413         }
 414
 415         /* We don't care about errors */
 416
 417         talloc_free(call);
 418 }
 419
 420 /*
 421   called when we get a new connection
 422 */
 423 static void ntp_signd_accept(struct stream_connection *conn)
 424 {
 425         struct ntp_signd_server *ntp_signd = talloc_get_type(conn->private_data,
 426                                                 struct ntp_signd_server);
 427         struct ntp_signd_connection *ntp_signd_conn;
 428         struct tevent_req *subreq;
 429         int rc;
 430
 431         ntp_signd_conn = talloc_zero(conn, struct ntp_signd_connection);
 432         if (ntp_signd_conn == NULL) {
 433                 stream_terminate_connection(conn,
 434                                 "ntp_signd_accept: out of memory");
 435                 return;
 436         }
 437
 438         ntp_signd_conn->send_queue = tevent_queue_create(conn,
 439                         "ntp_signd_accept");
 440         if (ntp_signd_conn->send_queue == NULL) {
 441                 stream_terminate_connection(conn,
 442                                 "ntp_signd_accept: out of memory");
 443                 return;
 444         }
 445
 446         TALLOC_FREE(conn->event.fde);
 447
 448         rc = tstream_bsd_existing_socket(ntp_signd_conn->tstream,
 449                         socket_get_fd(conn->socket),
 450                         &ntp_signd_conn->tstream);
 451         if (rc < 0) {
 452                 stream_terminate_connection(conn,
 453                                 "ntp_signd_accept: out of memory");
 454                 return;
 455         }
 456
 457         ntp_signd_conn->conn = conn;
 458         ntp_signd_conn->ntp_signd = ntp_signd;
 459         conn->private_data = ntp_signd_conn;
 460
 461         /*
 462          * The NTP tcp pdu's has the length as 4 byte (initial_read_size),
 463          * packet_full_request_u32 provides the pdu length then.
 464          */
 465         subreq = tstream_read_pdu_blob_send(ntp_signd_conn,
 466                                             ntp_signd_conn->conn->event.ctx,
 467                                             ntp_signd_conn->tstream,
 468                                             4, /* initial_read_size */
 469                                             packet_full_request_u32,
 470                                             ntp_signd_conn);
 471         if (subreq == NULL) {
 472                 ntp_signd_terminate_connection(ntp_signd_conn,
 473                                 "ntp_signd_accept: "
 474                                 "no memory for tstream_read_pdu_blob_send");
 475                 return;
 476         }
 477         tevent_req_set_callback(subreq, ntp_signd_call_loop, ntp_signd_conn);
 478 }
 479
 480 static const struct stream_server_ops ntp_signd_stream_ops = {
 481         .name                   = "ntp_signd",
 482         .accept_connection      = ntp_signd_accept,
 483         .recv_handler           = ntp_signd_recv,
 484         .send_handler           = ntp_signd_send
 485 };
 486
 487 /*
 488   startup the ntp_signd task
 489 */
 490 static void ntp_signd_task_init(struct task_server *task)
 491 {
 492         struct ntp_signd_server *ntp_signd;
 493         NTSTATUS status;
 494
 495         const struct model_ops *model_ops;
 496
 497         const char *address;
 498
 499         if (!directory_create_or_exist(lp_ntp_signd_socket_directory(task->lp_ctx), geteuid(), 0755)) {
 500                 char *error = talloc_asprintf(task, "Cannot create NTP signd pipe directory: %s",
 501                                               lp_ntp_signd_socket_directory(task->lp_ctx));
 502                 task_server_terminate(task,
 503                                       error, true);
 504                 return;
 505         }
 506
 507         /* within the ntp_signd task we want to be a single process, so
 508            ask for the single process model ops and pass these to the
 509            stream_setup_socket() call. */
 510         model_ops = process_model_startup(task->event_ctx, "single");
 511         if (!model_ops) {
 512                 DEBUG(0,("Can't find 'single' process model_ops\n"));
 513                 return;
 514         }
 515
 516         task_server_set_title(task, "task[ntp_signd]");
 517
 518         ntp_signd = talloc(task, struct ntp_signd_server);
 519         if (ntp_signd == NULL) {
 520                 task_server_terminate(task, "ntp_signd: out of memory", true);
 521                 return;
 522         }
 523
 524         ntp_signd->task = task;
 525
 526         /* Must be system to get at the password hashes */
 527         ntp_signd->samdb = samdb_connect(ntp_signd, task->event_ctx, task->lp_ctx, system_session(task->lp_ctx));
 528         if (ntp_signd->samdb == NULL) {
 529                 task_server_terminate(task, "ntp_signd failed to open samdb", true);
 530                 return;
 531         }
 532
 533         address = talloc_asprintf(ntp_signd, "%s/socket", lp_ntp_signd_socket_directory(task->lp_ctx));
 534
 535         status = stream_setup_socket(ntp_signd->task->event_ctx,
 536                                      ntp_signd->task->lp_ctx,
 537                                      model_ops,
 538                                      &ntp_signd_stream_ops,
 539                                      "unix", address, NULL,
 540                                      lp_socket_options(ntp_signd->task->lp_ctx),
 541                                      ntp_signd);
 542         if (!NT_STATUS_IS_OK(status)) {
 543                 DEBUG(0,("Failed to bind to %s - %s\n",
 544                          address, nt_errstr(status)));
 545                 return;
 546         }
 547
 548 }
 549
 550
 551 /* called at smbd startup - register ourselves as a server service */
 552 NTSTATUS server_service_ntp_signd_init(void)
 553 {
 554         return register_server_service("ntp_signd", ntp_signd_task_init);
 555 }